Power Tool Electric Tool History

In 1895, Germany overtone to create the world's first direct current drill. The shell made from cast iron, can drill a hole in 4 mm steel plate. Then appear the three-phase power frequency (50 hz) drill, but the motor speed can't exceed 3000 r/min. In 1914, a single-phase series motor driven power tools, motor speeds above 10000 r/min. In 1927, the power supply frequency is 150 ~ 200 hz frequency electric tool, it not only has the advantage of high single-phase series motor rotation speed, but also has the advantages of simple structure, reliable three-phase power frequency motor, but because of it need medium frequency power supply, current use is limited.